6 results on '"Bertotti M"'
Search Results
2. Unveiling the contribution of the reproductive system of individual Caenorhabditis elegans on oxygen consumption by single-point scanning electrochemical microscopy measurements.
- Author
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Santos CS, Macedo F, Kowaltowski AJ, Bertotti M, Unwin PR, Marques da Cunha F, and Meloni GN
- Subjects
- Animals, Electrodes, Genitalia, Microscopy, Electrochemical, Scanning, Caenorhabditis elegans, Oxygen Consumption
- Abstract
Metabolic analysis in animals is usually either evaluated as whole-body measurements or in isolated tissue samples. To reveal tissue specificities in vivo, this study uses scanning electrochemical microscopy (SECM) to provide localized oxygen consumption rates (OCRs) in different regions of single adult Caenorhabditis elegans individuals. This is achieved by measuring the oxygen reduction current at the SECM tip electrode and using a finite element method model of the experiment that defines oxygen concentration and flux at the surface of the organism. SECM mapping measurements uncover a marked heterogeneity of OCR along the worm, with high respiration rates at the reproductive system region. To enable sensitive and quantitative measurements, a self-referencing approach is adopted, whereby the oxygen reduction current at the SECM tip is measured at a selected point on the worm and in bulk solution (calibration). Using genetic and pharmacological approaches, our SECM measurements indicate that viable eggs in the reproductive system are the main contributors in the total oxygen consumption of adult Caenorhabditis elegans. The finding that large regional differences in OCR exist within the animal provides a new understanding of oxygen consumption and metabolic measurements, paving the way for tissue-specific metabolic analyses and toxicity evaluation within single organisms., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Author(s). Published by Elsevier B.V. All rights reserved.)
- Published
- 2021
- Full Text
- View/download PDF
3. Ultrasensitive microfluidic electrochemical immunosensor based on electrodeposited nanoporous gold for SOX-2 determination.
- Author
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Regiart M, Gimenez AM, Lopes AT, Carreño MNP, and Bertotti M
- Subjects
- Antibodies, Immobilized, Electrochemical Techniques, Gold, Hydrogen Peroxide, Immunoassay, Limit of Detection, Microfluidics, Biosensing Techniques, Metal Nanoparticles, Nanopores
- Abstract
An ultrasensitive and portable microfluidic electrochemical immunosensor for SOX-2 cancer biomarker determination was developed. The selectivity and sensitivity of the sensor were improved by modifying the microfluidic channel. This was accomplished through a physical-chemical treatment to produce a hydrophilic surface, with an increased surface to volume/ratio, where the anti-SOX-2 antibodies can be covalently immobilized. A sputtered gold electrode was used as detector and its surface was activated by using a dynamic hydrogen bubble template method. As a result, a gold nanoporous structure (NPAu) with outstanding properties, like high specific surface area, large pore volume, uniform nanostructure, good conductivity, and excellent electrochemical activity was obtained. SOX-2 present in the sample was bound to the anti-SOX-2 immobilized in the microfluidic channel, and then was labeled with a second antibody marked with horseradish peroxidase (HRP-anti-SOX-2) like a sandwich immunoassay. Finally, an H
2 O2 + catechol solution was added, and the enzymatic product (quinone) was reduced on the NPAu electrode at +0.1 V (vs. Ag). The current obtained was directly proportional to the SOX-2 concentration in the sample. The detection limit achieved was 30 pg mL-1 , and the coefficient of variation was less than 4.75%. Therefore, the microfluidic electrochemical immunosensor is a suitable clinical device for in situ SOX-2 determination in real samples., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier B.V. All rights reserved.)- Published
- 2020
- Full Text
- View/download PDF
4. Electrochemical microfluidic immunosensor based on TES-AuNPs@Fe 3 O 4 and CMK-8 for IgG anti-Toxocara canis determination.
- Author
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Jofre CF, Regiart M, Fernández-Baldo MA, Bertotti M, Raba J, and Messina GA
- Subjects
- Animals, Antibodies, Helminth blood, Biosensing Techniques instrumentation, Carbon chemistry, Electrochemical Techniques instrumentation, Equipment Design, Ferrosoferric Oxide chemistry, Humans, Immunoassay instrumentation, Limit of Detection, Porosity, Toxocariasis blood, Antibodies, Helminth immunology, Gold chemistry, Metal Nanoparticles chemistry, Microfluidic Analytical Techniques instrumentation, Toxocara canis immunology, Toxocariasis immunology
- Abstract
We report a microfluidic immunosensor for the electrochemical determination of IgG antibodies anti-Toxocara canis (IgG anti-T. canis). In order to improve the selectivity and sensitivity of the sensor, core-shell gold-ferric oxide nanoparticles (AuNPs@Fe
3 O4 ), and ordered mesoporous carbon (CMK-8) in chitosan (CH) were used. IgG anti-T. canis antibodies detection was carried out using a non-competitive immunoassay, in which excretory secretory antigens from T. canis second-stage larvae (TES) were covalently immobilized on AuNPs@Fe3 O4 . CMK-8-CH and AuNPs@Fe3 O4 were characterized by transmission electron microscopy, scanning electron microscopy, energy dispersive spectrometry, cyclic voltammetry, electrochemical impedance spectroscopy, and N2 adsorption-desorption isotherms. Antibodies present in serum samples immunologically reacted with TES, and then were quantified by using a second antibody labeled with horseradish peroxidase (HRP-anti-IgG). HRP catalyzes the reduction from H2 O2 to H2 O with the subsequent oxidation of catechol (H2Q) to p-benzoquinone (Q). The enzymatic product was detected electrochemically at_ 100 mV on a modified sputtered gold electrode. The detection limit was 0.10 ng mL-1 , and the coefficients of intra- and inter-assay variation were less than 6%, with a total assay time of 20 min. As can be seen, the electrochemical immunosensor is a useful tool for in situ IgG antibodies anti-T. canis determination., (Copyright © 2019 Elsevier B.V. All rights reserved.)- Published
- 2020
- Full Text
- View/download PDF
5. Amperometric microsensor based on nanoporous gold for ascorbic acid detection in highly acidic biological extracts.
- Author
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Kumar A, Furtado VL, Gonçalves JM, Bannitz-Fernandes R, Netto LES, Araki K, and Bertotti M
- Subjects
- Arabidopsis chemistry, Ascorbic Acid chemistry, Aspergillus fumigatus chemistry, Electrochemical Techniques instrumentation, Hydrogen-Ion Concentration, Limit of Detection, Microelectrodes, Nanopores, Oxidation-Reduction, Plant Extracts analysis, Plant Leaves chemistry, Porosity, Reproducibility of Results, Ascorbic Acid analysis, Electrochemical Techniques methods, Gold chemistry, Nanowires chemistry
- Abstract
Tuning the electrocatalytic properties of high surface area porous metallic frameworks like Nanoporous Gold (NPG) by tailoring the structure is a convenient strategy to design electrochemical sensors. Accordingly, an NPG-based sensitive, selective and robust electroanalytical platform was designed for the detection of ascorbic acid (AA) in acidic extracts of Aspergillus fumigatus fungus and Arabidopsis thaliana leaves. NPG films were electrodeposited on a gold microelectrode by potentiostatic electrodeposition and characterized by electron microscopy techniques, which confirmed the morphology and highly porous structure resembling nanowires-type pure gold fractals. The electrodeposition parameters, particularly deposition potential and time, were optimized to achieve large and selective amperometric detection of AA on the NPG modified electrodes. Faster electron transfer kinetics was manifested on the 0.3 V shift in overpotential and remarkable enhancement of the oxidation peak current as compared with bare gold electrode. Amperometric measurements were performed at 0.3 V vs. Ag/AgCl
(sat. KCl) in the highly acidic electrolyte solution employed to extract ascorbate from biological samples and minimize its autoxidation. The sensitivity of conventional Au-microelectrodes was increased about one thousand-fold upon modification with NPG film, reaching 2 nA μmol-1 L-1 . The detection limit for AA based on a linear current-concentration calibration plot was found to be 2 μmol L-1 . The NPG-based microsensor was demonstrated to be selective, reproducible and stable, and was employed for determinations of AA concentration in highly acidic biological extracts., (Copyright © 2019 Elsevier B.V. All rights reserved.)- Published
- 2020
- Full Text
- View/download PDF
6. Enhanced sensitivity of scanning bipolar electrochemical microscopy for O 2 detection.
- Author
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Santos CS, Conzuelo F, Eßmann V, Bertotti M, and Schuhmann W
- Abstract
The Scanning Bipolar Electrochemical Microscope (SBECM) allows precise positioning of an electrochemical micro-probe serving as bipolar electrode that can be wirelessly interrogated by coupling the electrochemical detection reaction with an electrochemiluminescent reporting process. As a result, the spatially heterogeneous concentrations of an analyte of interest can be converted in real time into a map of sample reactivity. However, this can only be achieved upon optimization of the analytical performance ensuring adequate sensitivity. Here, we present the evaluation and optimized operation of the SBECM for the detection of small changes in local O
2 concentrations. Parameters for achieving an improved sensitivity as well as possibilities for improving the signal-to-noise ratio in the optical signal readout are evaluated. The capability of the SBECM for O2 detection is shown at controlled conditions by recording the topography of a patterned sample and monitoring O2 evolution from a photoelectrocatalyst material., (Copyright © 2019 Elsevier B.V. All rights reserved.)- Published
- 2019
- Full Text
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